This disclosure generally relates to an air cycle machine utilized as part of an aircraft environmental control system (ECS).
An ECS provides a supply of conditioned air to an enclosure, such as an aircraft cabin and cockpit. The ACM is an integral part of the ECS. Conventional ACM's include at least two turbines and a compressor mounted along a common axis. The turbines and compressor are assembled using multiple shaft pieces and held together with a tie rod assembly. For example, the compressor may be mounted as a link between two shaft pieces. Typically, each shaft piece is machined to a desired tolerance in a separate operation and later assembled to the other pieces.
Disadvantageously, the tolerances from each component compound in assembly. This often results in misalignment of journal bearing portions of the ACM and leads to undesirable shaft loads, vibration, and imbalance during ACM operation. Furthermore, conventional assemblies often require complex and heavy components to hold the shaft pieces, turbines, and compressor together, such as tie rods and robust static structures.
Accordingly, it is desirable to develop and design improved ACM shafts and methods of fabricating ACM shafts.